The present invention relates to a machine for packing groups of cigarettes.
British Patent No. 2,138,382 relates to a machine for packing groups of cigarettes, which comprises a cigarette hopper with at least two outlets for respective groups of cigarettes; step-operated first conveying means, in turn comprising a pocket conveyor belt looped about two transmission pulleys defining, on the conveyor belt, an unloading branch, and a loading branch extending past the hopper outlets, and a number of first conveying pockets for respective groups of cigarettes equally spaced along the conveyor belt; reciprocating loading means which move through the hopper outlets to expel the groups of cigarettes from the outlets and feed the groups to the first conveying pockets; and continuous second conveying means with a number of second conveying pockets which travel through a loading station, located along the unloading branch of the first conveying means, to receive the groups of cigarettes from the first conveying pockets.
In the above patent, the second conveying means comprise a further endless conveyor belt, which supports the second conveying pockets equally spaced like the first conveying pockets, and which has a respective conveying branch extending through the loading station to the side of the unloading branch to enable, at each continuous operating period of the first conveying means, alignment of the first and second conveying pockets, and transfer of the groups of cigarettes from the first to the second conveying pockets.
The above known packing machine has several technical drawbacks which, with use, seriously impair the efficiency of the machine. That is, however well made using technically advanced materials, the endless conveyor belts are inevitably subject--due to wear and changing environmental conditions--to dimensional variations affecting, at times irreparably, the precise alignment of the first and second conveying pockets required to transfer the groups of cigarettes along the loading station. Moreover, though means are provided for correcting such dimensional variations, the situation is further compounded by the difficulty in restoring to optimum efficiency two conveying means operating structurally independently of each other.
EP-A-210531 discloses a machine for packing groups of cigarettes, which partially overcomes the aforementioned drawbacks and comprises a pocket conveyor having a plurality of pockets, which are designed for receiving respective groups of cigarettes and are advanced along a closed path and through a receiving station, wherein each pocket cooperates with the outlets of a hopper for receiving a relevant group of cigarettes, and a feeding station, wherein each pocket cooperates with a respective seat of a motorized wrapping wheel, around which the pocket conveyor is wound, for feeding the relevant group of cigarettes to the seat. The pocket conveyor has two opposite end pulleys, which divide the pocket conveyor into a lower branch, at which the receiving station is arranged, and an upper branch, at which the feeding station is arranged. The two opposite end pulleys are movable to and from each other to allow the pocket conveyor to advance continuously along the upper branch in phase with the continuously rotating wrapping wheel, and to allow the pocket conveyor to step-advance along the lower branch for cooperating with reciprocating loading means movable through the outlets of the hopper. The pocket conveyor has no belt and is designed to be substantially free of wear and of play.
The above known packing machine partially overcomes the aforementioned drawbacks, but is relatively complicated, and therefore expensive, owing to a branch of the pocket conveyor being continuously advanced and another branch of the pocket conveyor being step-advanced.